An electromagnetic motor requires high performance for reasons such as energy saving, CO2 reduction, or the like, and representative performance such as reduction in size and weight, high efficiency, high torque, high output, or the like, is remarkably improved every day. Electromagnetic motors can be generally classified according to a direction of magnetic flux into (1) radial flux motors, (2) axial flux motors, and (3) transversal flux motors. Among these, radial flux motors are particularly excellent in cost-performance, and widely used for various products in industrial fields as a representative mechanical element of a universal actuator. In addition, axial flux motors have a three-dimensional complex magnetic path configuration, and in particular, are applied in the field of medium/large-sized large-diameter thin motors.
On the other hand, transversal flux motors include a rotor having permanent magnets, and an armature having an annular coil and a stator core, for example. The annular coil is annularly formed about a rotary shaft. In addition, the stator core is constituted by, for example, a plurality of U-shaped cores (hereinafter referred to as U-shaped stator cores) surrounding the annular coil. According to the above-mentioned transversal flux motor, since multipolarization can be relatively easily realized, a large torque motor with a small size can be obtained. That is, in a radial flux motor or an axial flux motor, a dead space configured to allow insertion of coils into a plurality of slots is needed. On the other hand, in a transversal flux motor, for example, since the plurality of U-shaped stator cores may be arranged in parallel to a rotation direction of the rotary shaft, multipolarization is easily performed in general. In addition, the armature including the annular coil and the U-shaped stator cores has a structure in which a magnetic flux generated by the coil cannot easily leak to the outside. For this reason, generation efficiency of the magnetic field by the coil is increased, and in comparison with the radial flux motor or the axial flux motor having a coil end, reduction in size can be expected.
Incidentally, in rotating electrical machines, additional performance improvement is expected. On the other hand, when stiffness of a rotating electrical machine is decreased, noise may increase.